Capsules containing beverage ingredients, which are designed for producing a beverage in a beverage preparation device upon liquid injection into the capsules and by rotating the capsules around a central axis in the device are known in the prior art.
The principle consists in preparing a beverage by passing a liquid through beverage ingredients contained in the capsule using centrifugal forces. Thereby, liquid is usually injected in a central inlet area of the capsule before and/or during rotation of the capsule in order to make the liquid interact with the ingredients in the capsule, thus forming a beverage such as coffee, ground coffee, tea, or the like. The resulting beverage is then allowed to exit the capsule by means of at least one outlet aperture provided at a portion arranged radially outwards with respect to the central inlet area of the capsule.
A centrifugal coffee system employing the above-indicated principle is described in WO2008/148656. The membrane of a dedicated capsule is perforated by an injection member of the beverage preparation device in the central part of the membrane for injection of liquid and is simultaneously perforated in the peripheral part of the membrane by smaller piercing members for extraction of the beverage. In particular, a series of perforating members are present on an interface plate of the beverage machine for interacting with the membrane of the capsule. These perforating members aim at perforating the membrane at several locations of the membrane close to the periphery of the capsule respectively near a flange of the capsule. The created perforations enable the resulting beverage to leave the capsule by effect of the centrifugal pressure due to the high-speed rotation of the capsule in the beverage machine.
The known perforating means are in general pyramidal or conically shaped and provide a relatively low angle of inclination with respect to a longitudinal axis respectively a rotational axis of the respective perforation member. This arrangement of the perforating means however suffers the drawback that the membrane of the capsule will accumulate on the surface of the respective perforating member and will thus negatively affect and eventually even block the flow of beverage between the perforating member and the membrane.
EP 1 339 305 relates to a beverage preparation device comprising an essentially conical perforation means designed for producing inlet openings in a capsule face. Thereby, the conical perforating means and in particular a cutting edge thereof is arranged at an acute angle with respect to a longitudinal axis of a capsule.
Based on the known prior art teachings, it is thus desirable to provide perforating means for a beverage preparation device specifically designed to provide an homogeneously distributed flow of beverage coming out of the capsule and preventing the flow from being blocked by the perforating means, thereby overcoming the above-identified problems.